Utafiti huu unalinganisha usanidi tano wa injini za turbofan zenye bypass ya juu, zikiwemo za shafts mbili na shafts tatu, kwa kuzingatia gharama ya mzunguko wa maisha wa miaka 20, utendaji wa exergo-economic na viashiria vya mazingira. Miundo ya kihesabu ilitathminiwa kwa kubadilisha hali za uendeshaji kama joto la mazingira, unyevunyevu wa kiasi, Mach number ya ndege na altitude. Katika matokeo ya modeli, matumizi ya mafuta yalikuwa sehemu kubwa zaidi ya gharama, yakichangia takriban %60–75 ya gharama ya jumla ya mzunguko wa maisha kwa saa. Joto la mazingira, cruise altitude na Mach number zilibadilisha kwa kiasi kikubwa matokeo ya kiuchumi na thermodynamic, huku athari ya unyevunyevu wa kiasi ikiwa ndogo zaidi. Wakati wa takeoff, exergy destruction na inefficiencies za components zilijitokeza kama vyanzo vikuu vya hasara za kiuchumi, ilhali katika cruise umuhimu wa jamaa wa capital-investment costs uliongezeka. Kikwazo kikuu cha utafiti ni kwamba matokeo yanategemea validated computational engine models na assumptions maalum za kiuchumi, si jaribio la kimwili la fleet.

Utafiti pia unaonyesha kwamba kuangalia tu hourly cost rate huenda kusiwe kutosha kueleza hali halisi ya thermo-economic ya injini. Kwa mfano, kuongezeka kwa joto la mazingira au altitude katika baadhi ya hali kunaweza kupunguza total cost rate huku kukiongeza cost per unit of useful exergy. Kinyume chake, katika Mach range iliyochunguzwa, Mach number ya juu iliongeza exergy output katika nozzles na kupunguza specific exergy cost. Kwa hiyo, “gharama ya chini kwa saa” na “utendaji bora wa kiuchumi kwa kila unit ya useful exergy inayozalishwa” si dhana ileile.

Katika tathmini ya mazingira pia hakuna indicator moja inayofafanua picha nzima. Exergy-based environmental destruction coefficient na environmental destruction index zilipungua katika cruise ikilinganishwa na takeoff, huku environmental benign index ikiongezeka. Hata hivyo, specific CO₂ emission kwa thrust inayozalishwa ilikuwa juu zaidi katika cruise kwa cases zote. Kati ya configurations tano, Vaka 3 ilionyesha utendaji bora zaidi katika viashiria vitatu vya mazingira vinavyotegemea exergy wakati wa takeoff na cruise; kwa specific CO₂, Vaka 3 ilikuwa na thamani ya chini zaidi katika takeoff na Vaka 2 katika cruise.

Kwa mtazamo wa Türkiye: Matokeo yanaweza kutoa mfumo wa kimetodolojia unaoonyesha kwamba kwa commercial turbofan systems zinazotumika au kutathminiwa nchini Türkiye, joto la mazingira, flight profile, altitude na engine architecture vinapaswa kuzingatiwa kwa pamoja. Hata hivyo, hali za uendeshaji za utafiti zilichaguliwa hasa kuwakilisha eneo la Ghuba na hali ya hewa ya Kuwait, na economic model ilitumia assumptions mahususi za bei ya mafuta, operating hours, discount rate na maintenance cost. Kwa hiyo, dollar/hour values au rankings za injini katika utafiti hazipaswi kuhamishwa moja kwa moja kwa viwanja vya ndege, fleet mission profiles, maintenance contracts na fuel costs za Türkiye; re-validation kwa data za ndani inahitajika.

Swali kuu la utafiti ni nini?

Hoja ya kuanzia ya utafiti ni kwamba kutathmini high-bypass turbofans kwa thermodynamic efficiency pekee haitoshi kwa engine selection na maamuzi ya uendeshaji wa muda mrefu. Injini inaweza kuonyesha thermodynamic performance ya juu; lakini capital cost, maintenance expenses, fuel consumption na exergy destruction zikizingatiwa pamoja, matokeo tofauti ya kiuchumi yanaweza kujitokeza. Vivyo hivyo, total fuel consumption ndogo haimaanishi moja kwa moja environmental burden ndogo zaidi kwa useful thrust au exergy inayozalishwa.

Kwa hiyo watafiti walipanua energy na exergy analysis waliyoifanya hapo awali kwa configurations hizo hizo tano na kuzingatia maswali matatu makuu: gharama ya mzunguko wa maisha wa miaka 20 ya injini hubadilikaje katika hali tofauti za uendeshaji; exergy destruction pamoja na capital na operating expenses hubadilishwaje kuwa cost katika kiwango cha components; na environmental performance indicators za injini hizi zinazohusiana na CO₂ na exergy hutofautianaje katika takeoff na cruise?

Configurations tano za turbofan ziliundwaje?

Cases tano zilizochunguzwa zilitokana na injini halisi za high-bypass zinazotumika katika commercial aviation. Utafiti hauzitumi kama fleet measurements za moja kwa moja kutoka injini halisi, bali kama computational configurations zinazowakilisha architectures na performance characteristics tofauti.

Katika two-shaft architecture, fan, low-pressure compressor na low-pressure turbine, pamoja na high-pressure compressor na high-pressure turbine, hupangwa kupitia shaft systems mbili kuu; katika three-shaft architecture, intermediate-pressure compressor na intermediate-pressure turbine huongezwa. Utafiti unaonyesha kwamba katika three-shaft architecture, kugawanya compression na expansion work katika stages nyingi zaidi kunaweza kusawazisha exergo-economic burden katika baadhi ya components.

Modeli inategemea assumptions gani kuu?

Engine models zilitatuliwa katika steady-state conditions; transient regimes hazikuzingatiwa. Inlet air na exhaust gases zilimodeliwa kama ideal-gas mixtures zenye temperature-dependent thermophysical properties, working-fluid leakage ilipuuzwa na mabadiliko ya potential exergy hayakuzingatiwa. Ilidhaniwa kwamba fuel combustion ni complete, nitrogen hufanya kama non-reacting species na Jet A-1 hutumiwa katika configurations zote. Thermal-energy loss katika combustion chamber ilichukuliwa kuwa %2 ya total heat release. Reference environmental conditions zilikuwa 288,15 K na 101,3 kPa.

Lifecycle cost ilihesabiwaje?

Lifecycle Costing (LCC) huunganisha initial investment cost ya injini na operating-maintenance pamoja na fuel costs katika service life ya miaka 20, kisha huondoa salvage/residual value mwisho wa maisha. Katika source, Equation (1) imetolewa hivi:

\[ LCC = C_{inst} + \left[C_{O\&M}+C_{fuel}\right]H-C_{salvage} \]

Source note: Katika equation, alama ya initial investment cost inaonekana kama \(C_{inst}\), lakini katika maelezo ya maandishi yanayofuata dhana hiyo hiyo imeandikwa \(C_{ini}\). Tofauti hii ya alama imedumishwa kama ilivyo kwenye source na haijasahihishwa kimya kimya kuwa notation moja.

Present-value method ilitumika kubadilisha annual future payments kuwa equivalent economic value katika mwaka wa mwanzo:

\[ PV=A_0\sum_{t=1}^{n}\frac{1}{(1+d)^t} = A_0\frac{(1+d)^n-1}{d(1+d)^n} \]

Hapa \(A_0\) ni equal annual payment, \(d\) ni discount rate na \(n\) ni evaluation period. Main financial assumptions zilizotumika ni hizi:

Annual operating times tofauti zilitumika kuwakilisha short/medium-haul na long-haul mission profiles zinazohusishwa na injini. Kwa hiyo, tofauti za total cost kati ya cases haziathiriwi na engine efficiency pekee bali pia na assumptions za annual utilization.

Kwa nini fuel iko katikati ya lifecycle cost?

Katika cases zote tano, fuel expense huchangia takriban %60–75 ya total hourly lifecycle cost katika kipindi cha miaka 20 cha modeli. Hii ina maana kwamba operating conditions zinazobadilisha fuel consumption zinaweza kuathiri kwa nguvu long-term cost ranking.

Katika takeoff analysis, ambient temperature ilipopanda kutoka 288 K hadi 320 K, hourly lifecycle cost ya Vaka 3 ilishuka kwenye graph kutoka takriban 10.500 US$/hour hadi 9000 US$/hour. Source inatafsiri tofauti hii kuwa karibu 1500 US$/hour. Katika Vaka 4 na Vaka 5, temperature-dependent difference ni takriban 1000 US$/hour, huku Vaka 2 ikiripotiwa kuwa na moja ya temperature sensitivities ndogo zaidi, karibu 200 US$/hour.

Hili linaweza kuonekana la kushangaza kwa sababu thermodynamic performance ni favourable zaidi katika 288 K. Kwa maelezo ya watafiti, lower air density katika 320 K inaweza kupunguza total air mass flow na absolute fuel flow kupitia injini, hivyo kupunguza hourly fuel cost. Lakini hii haimaanishi kuwa mazingira yenye joto hufanya injini iwe thermo-economically efficient zaidi. Exergo-economic analysis ya baadaye inaonyesha kwamba kadiri joto linavyoongezeka, useful exergy output inaweza kupungua kwa kasi zaidi na cost per unit exergy ikaongezeka.

Kwa nini relative humidity ilibaki secondary variable?

Relative humidity ilipoongezwa kutoka %30 hadi %100, mabadiliko ya lifecycle cost yalikuwa madogo sana kuliko athari za ambient temperature, Mach number na altitude. Katika Monte Carlo uncertainty assessment, hourly LCC effect ya humidity change ilibaki kati ya 18–304 US$/hour na probability ya trend kubadilisha mwelekeo ilikadiriwa kuwa %36. Kwa hiyo watafiti waliainisha relative humidity kama secondary economic driver.

Muundo unaofanana unaonekana katika exergo-economic component analysis. Katika Vaka 5, total exergy destruction pamoja na capital cost ya combustion chamber ni takriban 2200 US$/hour, na kuongeza relative humidity kutoka %30 hadi %100 hakubadilishi sana dominant cost structure hii. Tofauti inayoonekana zaidi ilionekana katika intermediate-pressure turbine na source ikaieleza kuwa mabadiliko ya zaidi kidogo ya %6.

Kwa nini source inahitaji kusomwa kwa uangalifu kuhusu Mach number?

Layers tofauti za analysis hazionyeshi athari ya Mach number kwa economic indicators kwa namna ileile. Katika numerical explanation ya Figure 3, hourly lifecycle cost ya Vaka 3 katika Mach 0,90 imetolewa kuwa karibu 4000 US$/hour, huku katika Mach 0,65 ikitajwa kuwa karibu 600 US$/hour chini. Kwa Vaka 4 na Vaka 5 pia hourly LCC ya chini imeelezwa kwa lower Mach value.

Hata hivyo, maelezo yanayofuata mara moja yanasema kwamba higher Mach number iliyochunguzwa hutoa better fuel efficiency na lower lifecycle cost. Maelezo haya mawili hayalingani kikamilifu. Kwa hiyo, kwa uaminifu kwa source data, haiwezekani kutoa hitimisho moja lisilo na mgongano kuhusu direction ya Mach number effect kwenye hourly LCC.

Kwa upande mwingine, exergo-economic nozzle analysis inaonyesha trend iliyo wazi zaidi: katika Vaka 3, Mach number inapoongezeka kutoka 0,65 hadi 0,90, total cost rate ya fan na core nozzles huongezeka huku specific exergy cost ikipungua. Watafiti wanaeleza hili kwa ram effect yenye nguvu zaidi kuongeza inlet stagnation pressure na temperature, huku exergy output ikikua kwa kasi zaidi kuliko cost increase. Kwa hiyo, jambo linaloweza kusemwa kwa uhakika kuhusu higher Mach ni kwamba katika range iliyochunguzwa specific exergy cost inaboreka; hili lazima litenganishwe wazi na hourly lifecycle cost.

Altitude hubadilishaje cost na exergy performance?

Cruise altitude ilipoongezwa kutoka 8000 m hadi 11.000 m, Figure 3 inaonyesha hourly ownership cost ikipungua katika cases zote. Kwa Vaka 3 kupungua kwa karibu 1200 US$/hour kuliripotiwa, kwa Vaka 4 karibu 750 US$/hour, kwa Vaka 5 karibu 600 US$/hour, na kwa cases nyingine mbili karibu 300 US$/hour.

Hata hivyo, specific-cost assessment katika nozzle level inaonyesha dimension tofauti. Katika Vaka 1, altitude inapoongezeka kutoka 8000 hadi 11.000 m, total cost rate ya fan na core nozzles hupungua huku cost per useful exergy ikiongezeka. Lower air density na mass flow hupunguza hourly economic burden ya system lakini zinaweza kupunguza useful-exergy production kwa kasi zaidi. Kwa hiyo, hourly cost ya chini haipaswi kutafsiriwa moja kwa moja kuwa thermo-economic efficiency ya juu.

Uncertainty analysis iliunga mkono trends kuu kwa kiwango gani?

Ili kupima kama lifecycle-cost results ni nyeti kupita kiasi kwa economic assumptions, Monte Carlo uncertainty propagation ilifanywa kwa samples 50.000 za Latin Hypercube. Triangular distribution ya ±%15 ilitumika kwa initial capital cost na fuel cost, %2–4 kwa discount rate, %4–6 kwa operation-and-maintenance factor, na %5–15 triangular distribution kwa residual value; annual operating hours ziliwakilishwa na bounded normal distribution ya ±%5. Parameters zilidhaniwa kuwa independent.

Monte Carlo analysis inaonyesha kwamba effects za ambient temperature na altitude zilibaki chini ya economic uncertainties zilizotumika. Magnitude difference ya Mach change pia ilibaki robust katika sampling; hata hivyo, kwa sababu source ina textual inconsistency kuhusu direction ya LCC iliyoelezwa hapo juu, Monte Carlo result haiwezi kuondoa contradiction hiyo ya uhariri.

Exergo-economic analysis inapima nini?

Exergo-economic analysis inaunganisha thermodynamic irreversibility katika component na capital pamoja na operating cost za component hiyo katika framework moja ya tathmini. Cost balance ya steady-state component imefafanuliwa kwenye source hivi:

\[ \sum_e \dot{C}_{e,k}+\dot{C}_{w,k} = \dot{C}_{q,k}+\sum_i\dot{C}_{i,k}+\dot{Z}^{T}_{k} \]

Hapa \(\dot{C}_{i,k}\) na \(\dot{C}_{e,k}\) zinawakilisha cost rates za inlet na outlet exergy streams, \(\dot{C}_{w,k}\) cost rate ya work transfer, \(\dot{C}_{q,k}\) cost rate ya heat transfer, na \(\dot{Z}^{T}_{k}\) investment na operation-maintenance cost ya component.

Kiasi ambacho unit cost ya product exergy huongezeka ikilinganishwa na fuel-exergy cost kinaelezwa na relative cost difference \(r_k\):

\[ r_k= \frac{c_{p,k}-c_{f,k}}{c_{f,k}} = \frac{1-\eta_{ex,k}}{\eta_{ex,k}} + \frac{\dot{Z}^{CI}_{k}+\dot{Z}^{OM}_{k}} {c_{f,k}\dot{E}_{p,k}} \]

Exergo-economic factor \(f_k\) hupima share ya capital na operation-maintenance cost katika total economic loss:

\[ f_k= \frac{\dot{Z}_k} {\dot{Z}_k+c_{f,k}\left(\dot{E}_{d,k}+\dot{E}_{L,k}\right)} \]

Low \(f_k\) inaonyesha kwamba cost inatokana zaidi na exergy destruction na losses; high \(f_k\) inaonyesha investment na operating costs kuwa dominant kwa kiasi kikubwa zaidi. Kwa hiyo optimal improvement strategy kwa engine component ileile inaweza kuwa tofauti kati ya takeoff na cruise.

Kwa nini combustion chamber inajitokeza wakati wa takeoff?

Katika Vaka 1 wakati wa takeoff, combustion chamber ina highest \(r_k\), huku \(f_k\) ikiwa karibu na zero. Watafiti wanaunganisha hili na strong irreversibilities zinazotokana na fuel-air mixing, chemical reactions na high-temperature gradients wakati wa combustion. High fuel flow na high combustion temperatures wakati wa takeoff huongeza zaidi effect hii.

High-pressure na low-pressure turbines pamoja na high-pressure compressor pia huzalisha significant exergy-destruction costs wakati wa takeoff. Katika Vaka 1, \(f_k\) values za major components zote kuwa chini ya %50 wakati wa takeoff inaonyesha kwamba economic loss inaathiriwa zaidi na thermodynamic irreversibilities kuliko capital cost.

Kwa nini cost structure hubadilika katika cruise?

Katika cruise, engine mass flow na combustion temperature hupungua, lakini capital cost ya physical engine haiondoki. Hivyo exergy-destruction cost hupungua huku relative share ya investment cost katika total cost ikiongezeka. Katika Vaka 1, \(f_k\) ya high-pressure compressor inakaribia %80 katika cruise. Katika three-shaft architecture ya Vaka 4, cruise \(f_k\) ya high-pressure turbine inafikia karibu %73.

Katika three-shaft Vaka 4, kuongezwa kwa intermediate-pressure compressor na intermediate-pressure turbine kunasambaza compression na expansion work katika stages nyingi zaidi. Source inaeleza kwamba hii inafanya relative cost differences kati ya components kuwa balanced zaidi kuliko Vaka 1 na inaweza kupunguza tendency ya three-shaft architecture ku-concentrate exergo-economic burden kwenye component moja.

Kwa nini specific exergy cost inaweza kuwa na maelezo zaidi kuliko hourly cost?

Katika fan na core nozzles za Vaka 4, ambient temperature inapoongezeka kutoka 288 K hadi 320 K, total cost rate hupungua huku specific cost ikiongezeka. Kwa sababu hewa ya joto hupunguza mass flow na total amount of energy processed, system huonekana kutumia gharama kidogo kwa saa; lakini useful exergy output hupungua kwa kasi zaidi, hivyo economic cost ya kila GJ ya useful exergy huongezeka.

Behavior inayofanana inaonekana katika Vaka 1 altitude inapoongezeka. Kinyume chake, katika Vaka 3, Mach number inapoongezeka kutoka 0,65 hadi 0,90, nozzle cost rate huongezeka huku specific cost ikipungua. Kwa hiyo moja ya main thermo-economic messages za utafiti ni kwamba total dollar/hour value haipaswi kutumiwa peke yake kama efficiency indicator.

Environmental indicators zilifafanuliwaje?

Mbali na direct specific CO₂ emission, watafiti walitumia environmental indicators tatu zinazotegemea exergy. Environmental destruction coefficient \(C_{ed}\) imefafanuliwa kama inverse ya exergetic efficiency ya injini:

\[ C_{ed}=\frac{1}{\eta_{ex}} \]

Ideal reference value ni 1; kadiri value inavyokaribia 1, performance inachukuliwa kuwa favourable zaidi.

Environmental destruction index \(\Theta_{edi}\) hutathmini ratio ya exergy loss na exergy destruction kwa fuel exergy pamoja na environmental destruction coefficient:

\[ \Theta_{edi} = \left[ \frac{E_l+E_d}{E_f} \right]C_{ed} \]

Katika indicator hii ideal value inakaribia zero. Environmental benign index \(\Theta_{ebi}\) ni inverse yake:

\[ \Theta_{ebi}=\frac{1}{\Theta_{edi}} \]

Kwa hiyo lower values ni favourable kwa \(C_{ed}\) na \(\Theta_{edi}\), huku higher value ikiwa favourable kwa \(\Theta_{ebi}\).

Vaka 3 inatoa environmental destruction coefficient ya chini zaidi katika takeoff na cruise: 1,67 na 1,37 mtawalia. Case hiyo hiyo imefikia values za chini zaidi katika environmental destruction index na values za juu zaidi katika environmental benign index.

Jedwali linaonyesha kwamba Vaka 3 ni configuration yenye favourable result zaidi katika exergy-based indicators katika operating regimes zote mbili. Hata hivyo, indicators hizi tatu si direct emissions inventory wala full lifecycle environmental-impact analysis; watafiti wanasema hili wazi.

Kwa nini specific CO₂ result inaleta ranking tofauti?

Specific CO₂ inaelezwa katika kg/(hour·kN) kwa ku-normalize kiasi cha CO₂ kinachotolewa kwa saa dhidi ya thrust inayozalishwa. Katika study, specific CO₂ ilikuwa juu zaidi katika cruise kuliko takeoff kwa cases zote tano. Sababu ni kwamba ingawa total fuel consumption hupungua katika cruise, thrust hupungua kwa kasi zaidi, hivyo CO₂ kwa kila unit ya thrust inayozalishwa huongezeka.

Specific CO₂ ya chini zaidi ilipatikana katika Vaka 3 wakati wa takeoff na Vaka 2 wakati wa cruise. Three-shaft Vaka 4 na Vaka 5 zilikuwa upande usio favourable zaidi kwa specific CO₂, hasa katika cruise. Kwa kuwa source graph haikutoa exact numbers katika separate table ndani ya text, hakuna exact CO₂ values zilizoundwa kutoka kwa graph hapa.

Matokeo yanayoungwa mkono na utafiti

• Chini ya cost assumptions zilizochunguzwa, fuel consumption huchangia takriban %60–75 ya hourly lifecycle cost ya miaka 20.
• Ambient temperature, altitude na Mach number hubadilisha economic na thermo-economic indicators kwa nguvu zaidi kuliko relative humidity.
• Katika takeoff, component inefficiencies na exergy destruction; katika cruise, capital cost huwa relatively important zaidi.
• Combustion chamber ni moja ya major exergo-economic loss sources, hasa katika takeoff.
• Lower hourly cost rate haimaanishi kila wakati better thermo-economic performance.
• Vaka 3 inatoa favourable result zaidi katika takeoff na cruise wakati \(C_{ed}\), \(\Theta_{edi}\) na \(\Theta_{ebi}\) zinatathminiwa kwa pamoja.
• Specific CO₂ ranking inategemea flight regime: Vaka 3 ina lower value katika takeoff na Vaka 2 katika cruise.
• Athari ya relative humidity kwenye lifecycle cost ni ndogo kuliko main operating variables nyingine.

Matokeo ambayo utafiti hauungi mkono au haukupima

• Haijaonyeshwa kwamba cases tano zitatoa dollar/hour costs zilezile kwa miaka 20 katika real airline fleets.
• Haijathibitishwa kwamba commercial engine moja maalum ni “best engine” katika routes, climates au operators wote.
• Exergy-based environmental indicators si full lifecycle emissions inventory wala kipimo cha all non-CO₂ climate effects za aviation.
• Model haijumuishi baadhi ya real-engine effects kama transient operating regimes na working-fluid leakage.
• Economic impacts za compressor fouling, blade erosion na hot-section degradation kutokana na sand/dust ingestion hazijamodeliwa moja kwa moja.
• Hakuna direct numerical transfer inayoweza kufanywa kutoka temperature/environmental conditions za Gulf region kwenda operating costs nchini Türkiye.
• Kwa sababu ya source-internal inconsistency katika Mach–LCC description ya Figure 3, haiwezekani kutoa conclusion moja kwamba higher Mach number kwa uhakika inapunguza au inaongeza hourly lifecycle cost.

Mbinu na Matokeo ya Utafiti

Computational framework

Msingi wa thermodynamic wa utafiti ni turbofan performance model iliyotengenezwa katika Part I ya research series hii na ku-validate dhidi ya manufacturer data na published engine data. Utafiti wa sasa umepanua thermodynamic outputs hizo kwa lifecycle cost, SPECO-based exergo-economic calculation na exergy-based environmental indicators. Exergo-economic na lifecycle models zimetekelezwa katika MATLAB R2022b. Waandishi pia wanasema GasTurb 14 na MATLAB R2022b zilitumika katika engine modeling na analysis.

Operating conditions zilizochunguzwa

Katika lifecycle sensitivity analysis, lower na upper operating points za environmental na flight parameters zilitumika:

• Ambient temperature: 288 K na 320 K
• Relative humidity: %30 RH na %100 RH
• Cruise Mach number: 0,65 na 0,90
• Cruise altitude: 8000 m na 11.000 m

Katika component-level exergo-economic comparisons, takeoff reference ilikuwa 101,3 kPa, 288,15 K na %30 relative humidity; cruise reference ilikuwa Mach 0,8 na 8000 m.

Discounted fuel-cost differences

Fuel-cost difference kati ya more-efficient na less-efficient operating points za injini ilibadilishwa kuwa present value katika 20-year discount process. Annual opportunity gain imefafanuliwa kwenye source kwa relation hii:

\[ CF=[C_{fuel}]_{VR}-[C_{fuel}]_{OPT} \]

na present value kwa miaka:

\[ CF_{PV} = \frac{CF_1}{(1+d)^1} + \frac{CF_2}{(1+d)^2} +\cdots+ \frac{CF_n}{(1+d)^n} \]

Katika ambient-temperature variation, Vaka 3 ilionyesha largest discounted fuel-cost difference, karibu 1200 US$/hour. Katika Mach 0,65–0,90 comparison, Vaka 3 tena ilitoa highest difference ya karibu 500 US$/hour. Altitude ilipobadilishwa kati ya 8000–11.000 m, difference kwa Vaka 3 ilikuwa karibu 1200 US$/hour. Humidity effect ilikuwa ndogo zaidi; largest value iliripotiwa katika Vaka 5 kuwa karibu 300 US$/hour.

SPECO equation systems

Katika exergo-economic solution, costs ziliwekwa kwa exergy streams za kila engine component na auxiliary cost relations zilitumika kupata equations huru za kutosha. Kwa two-shaft engine, Appendix A inatumia equations A1–A15 kujenga 14 independent cost equations kwa unknowns 14; kwa three-shaft engine, equations A16–A30 zinaunda independent cost system ya equations 15 huru kwa unknowns 15.

Muundo huu unaunganisha capital cost na exergy-flow cost za fan, low/high-pressure compressors, combustion chamber, high/low-pressure turbines, intermediate-pressure turbine katika three-shaft architecture na fan/core nozzles zinazohusiana katika matrix solution moja.

Component-level key findings

• Vaka 1: Katika takeoff, combustion chamber ina highest relative cost difference na exergo-economic factor karibu zero. Katika cruise, \(f_k\) ya high-pressure compressor inakaribia %80.
• Vaka 4: Katika three-shaft architecture, intermediate-pressure compressor na turbine zinasambaza cost burden kwa components nyingi zaidi. Katika cruise, \(f_k\) ya high-pressure turbine ni karibu %73.
• Vaka 2: Katika comparison ya 288 K na 320 K, combustion chamber ndiyo component kubwa zaidi ya total exergy destruction na investment cost; hot operating condition inaathiri fan, combustion chamber na high-pressure turbine kwa viwango tofauti.
• Vaka 5: Katika %30–%100 relative-humidity change, cost hierarchy kwa kiasi kikubwa inabaki; combustion chamber inabaki dominant kwa karibu 2200 US$/hour.
• Vaka 3: Mach inapoongezeka, cost rate ya fan na core nozzles huongezeka lakini specific exergy cost hupungua.

Kusoma environmental results kwa pamoja

Exergy-based environmental indicators zinakuwa favourable zaidi katika cruise kuliko takeoff kwa cases zote: \(C_{ed}\) na \(\Theta_{edi}\) hupungua na \(\Theta_{ebi}\) huongezeka. Kinyume chake, specific CO₂ huongezeka katika cruise kwa cases zote. Matokeo haya mawili hayapingani kwa sababu indicators zinajibu physical questions tofauti. Exergy indicators hutathmini thermodynamic resource use na losses, huku specific CO₂ iki-normalize carbon dioxide inayotolewa kwa thrust inayozalishwa.

Kipengele cha 7 cha conclusion kinasema Vaka 3 ilitoa “best/lowest” values kwa environmental indicators zote tatu. Kwa definition ya source yenyewe katika Equation (19), kauli hii si technically correct kwa \(\Theta_{ebi}\): higher value ni better kwa environmental benign index. Katika Table 6, Vaka 3 kwa kweli inatoa best result, lakini kwa highest \(\Theta_{ebi}\).

Main limitations za utafiti

Interpretation ya results inategemea seven main model assumptions na economic inputs. Engines zilimodeliwa katika steady state, transient effects na working-fluid leakage zikaachwa, ideal-gas approach ikatumika na complete combustion ikadhaniwa. Economic inputs kama fuel price, capital costs, annual flight hours, maintenance rates na discount rate si costs ambazo real airline kwa uhakika itakutana nazo katika future.

Ingawa uncertainty analysis inapima athari ya reasonable variation katika inputs hizi kwa main trends, model haijumuishi all real-world uncertainties. Kama waandishi wanavyosisitiza katika future-work recommendations, modeling correlations kati ya parameters na kujenga more advanced stochastic operating conditions bado ni maeneo ya future research.

Pia sand na dust ingestion, compressor fouling, blade erosion na hot-section wear, ambazo zinaweza kuwa muhimu katika engine operation katika Gulf geography, hazijajumuishwa katika economic-exergetic model ya sasa. Watafiti wanataja hili kama research gap muhimu kwa future work.

Maelezo ya Chanzo na Mbinu

Kichwa kamili cha asili cha utafiti: Comparative Exergo-Economic, Exergo-Environmental, and Lifecycle Cost Analysis of High-Bypass Turbofan Engine Configurations

Waandishi: Abdulrahman S. Almutairi; Hamad H. Almutairi; Abdulrahman H. Alenezi; Hamad M. Alhajeri.

Mpangilio wa waandishi: Mpangilio wa asili katika source umehifadhiwa kabisa. Source haina taarifa ya co-first author au equal contribution.

Mwandishi anayewajibika: Abdulrahman S. Almutairi.

Taasisi: Department of Mechanical Power and Refrigeration Technology, College of Technological Studies, Public Authority for Applied Education and Training, Shuwaikh, P.O. Box 42325, Kuwait City 70654, Kuwait.

Aina ya chanzo: Peer-reviewed research article inayounganisha computational thermodynamics/modeling, lifecycle-cost analysis, exergo-economic assessment na exergo-environmental assessment.

Jarida: Aerospace

Mchapishaji: MDPI

Volume / issue / article number: 13(7), 614

Tarehe ya kuchapishwa: 6 Julai 2026

DOI: 10.3390/aerospace13070614

Kiungo rasmi cha chapisho:MDPI — Aerospace 13(7), 614

Kiungo cha DOI:https://doi.org/10.3390/aerospace13070614

Leseni: Creative Commons Attribution 4.0 International (CC BY 4.0).

Peer-review status: Makala ni research article iliyochapishwa katika peer-reviewed, open-access journal Aerospace.

Ufadhili: Waandishi waliripoti kuwa utafiti haukupokea external funding.

Data availability: Imeelezwa kwamba original contributions za study ziko ndani ya article na maswali ya ziada yanaweza kuelekezwa kwa corresponding author.

Conflict of interest: Waandishi hawakuripoti conflict of interest.

Author contributions: Conceptualization Abdulrahman S. Almutairi na Hamad H. Almutairi; methodology waandishi hao hao wawili; software Abdulrahman S. Almutairi, Hamad H. Almutairi na Hamad M. Alhajeri; validation waandishi hao hao watatu; formal analysis Abdulrahman H. Alenezi na Hamad H. Almutairi; investigation waandishi wote wanne; resources Abdulrahman S. Almutairi; data curation Abdulrahman H. Alenezi na Hamad M. Alhajeri; initial draft Abdulrahman S. Almutairi, Hamad H. Almutairi na Hamad M. Alhajeri; review and editing Abdulrahman S. Almutairi na Hamad H. Almutairi; visualization Hamad M. Alhajeri; supervision Abdulrahman S. Almutairi na Hamad H. Almutairi; project administration Abdulrahman S. Almutairi.

Nafasi katika series: Utafiti ni mwendelezo wa Part I iliyochunguza energy na exergy performance ya engine configurations hizo hizo. Utafiti wa sasa unapanua framework kwa kuongeza economic na environmental assessment.

Bibliographic inconsistency note: Katika reference [36] ya study ya sasa, Part I imetajwa kama “Aerospace 2025, 13, 27”. Official journal citation ya Part I ni “Aerospace 2026, 13, 27”; study ilichapishwa online tarehe 26 Desemba 2025. Kwa hiyo neno “2025” katika source ya sasa halijabadilishwa kimya kimya; official bibliographic record imeelezwa tofauti.

Equation note: Katika Lifecycle Cost Equation (1), initial capital term imeandikwa \(C_{inst}\), na katika explanation inayofuata \(C_{ini}\) imetumika. Source-internal symbol difference hii imehifadhiwa.

Mach–LCC inconsistency: Numerical explanation ya Figure 3 inatoa higher hourly lifecycle costs kwa Mach 0,90 kuliko Mach 0,65, huku text inayofuata ikisema higher Mach value hutoa lower LCC. Kwa hiyo Verianla text haijalazimisha direction ya hourly LCC kuwa conclusion moja. Separate exergo-economic result kwamba Mach increase inapunguza specific exergy cost inaungwa mkono wazi na source.

Environmental-indicator terminology note: Kauli ya “lowest in all three indicators” katika conclusion haipatani na mathematical definition ya \(\Theta_{ebi}\). Vaka 3 inatoa best environmental-benign-index result kwa highest value.

Scientific boundary: Utafiti unatathmini computational configurations tano zilizotokana na injini halisi. Matokeo si 20-year observational study katika real airline fleet. Transient engine-performance regimes, baadhi ya real operating effects na long-term degradation kutokana na sand/dust hazijajumuishwa katika economic model. Matokeo yanapaswa kutathminiwa ndani ya thermodynamic model, mission profiles na economic assumptions zilizotumiwa.

Mbinu ya kutengeneza maudhui: Maelezo haya ya Verianla yanategemea source study iliyochunguzwa pekee kwa scientific findings. Hakuna new experimental result, new performance value, new emissions data au mechanism isiyokuwapo kwenye source iliyoongezwa kutoka external sources. External verification imewekewa mipaka kwenye study identity, official publication record, peer-review status na Part I bibliographic record.